1. Field of the Invention
This invention relates generally to an apparatus for heating and forming sheet material and more particularly to a food cooking apparatus for preparing a V-shaped Mexican food product known as a taco shell.
2. Description of the Prior Art
A taco is a popular Mexican food made by folding a tortilla (a thin, flexible, round cake made from corn flour dough called "masa") into a V-shaped shell, frying it crisp, and stuffing it with various fillings. The technology of this application deals with machines for automatically shaping and cooking the tortillas to make them into taco shells.
Masa is made by mixing corn flour with about an equal weight of water. A tortilla is made by shaping masa into a relatively thin pancake-shaped disk, which is cooked enough to cohere the product, but leave it flexible. Tortillas are made into various sizes, from a few inches in diameter up to two feet. However, most tortillas are between 3 and 9 inches in diameter. Typically the tortilla is fried for 20-30 seconds in hot (350.degree. F. to 400.degree. F.) cooking oil to form a crisp taco shell.
The cooking oil is an edible vegetable oil (usually coconut oil, soybean oil, or cottonseed oil) which is subject to deterioration by oxidation during the cooking process.
The masa tortilla is extremely fragile and must be moved with great care through the cooking oil or it will tear. Similarly after cooking the tortilla, now in the form of a taco shell, must be carefully removed from the apparatus and gingerly transported to a remote station for packaging.
Prior to this invention various types of apparatus for preparing taco shells have been developed. A common drawback of the prior art devices is their inability to automatically produce, in a trouble-free manner, large quantities of taco shells of uniform high quality.
Other drawbacks of the prior art devices include the use of inordinately large quantities of cooking oil and, in certain cases, the highly undesirable necessity of operator handling of the food product at various points during the cooking and packaging process.
One of the most successful prior art devices ever developed is described in my previously issued U.S. Pat. No. 3,766,846. The apparatus of the present invention constitutes an improvement of the apparatus described in this patent.
In addition to the prior art devices described and cited in my previously issued patent, I am familiar with the following patents which comprise the closest art of which I am aware and serve to clearly illustrate the novelty of the present invention:
U.S. Pat. Nos. 3,880,065--Stickle;
3,763,764--Schy;
3,680,474--Brown.